Medial fibroplasia of the renal artery.

“Medial fibroplasia” is a term used by McCormack et al. to designate the most common of the various nonatherosclerotic lesions which has a characteristic string-of-beads appearance on arteriograms (1–3). The term replaces “fibromuscular hyperplasia,” originally used to describe a specific, nonatherosclerotic lesion of the renal artery (4, 8) but which came to be applied to various lesions that have dissimilar arteriographic and histologic patterns. McCormack et al. classified the nonatherosclerotic lesions according to the primary site of involvement in the arterial wall and have shown a correlation between the histologic and the arteriographic appearance of the lesions. These have been termed medial fibroplasia, subadventitial fibroplasia, intimal fibroplasia, and fibromuscular hyperplasia (1). In this classification, the term fibromuscular hyperplasia is reserved for one of the nonatherosclerotic lesions in which there is hypertrophy of the muscle in the media as originally described, and our experience...